1. Field of the Invention
The subject invention relates to painter's equipment and painting methods and, more specifically, to methods of applying paint to a surface exclusive of a shielded further surface or object, to work surface shields, masks and protectors, and to paint shields and shielding assemblies.
2. Disclosure Statement
This disclosure statement is made pursuant to the duty of disclosure imposed by law and formulated in 37 CFR 1.56(a). No representation is hereby made that information thus disclosed in fact constitutes prior art inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends on uncertain and inevitably subjective elements of substantial likelihood and reasonableness, and inasmuch as a growing attitude appears to require citation of material which might lead to a discovery of pertinent material though not necessarily being of itself pertinent. Also, the following comments contain conclusions and observations which have only been drawn or become apparent after conception of the subject invention or which contrast the subject invention or its merits against the background of developments subsequent in time or priority.
There certainly has been no dearth of proposals in the area of paint shields, painting techniques, wall protectors, surface guards and the like, as may, for instance, be seen from the wall protector disclosed in U.S. Pat. No. 456,775, issued July 28, 1891, the wall protector disclosed in U.S. Pat. No. 624,796, issued May 9, 1899, the wall protecting device disclosed in U.S. Pat. No. 695,965, issued Mar. 25, 1902, the elaborately angled paint guard of U.S. Pat. No. 1,386,706, issued Aug. 9, 1921, the mop board protector of U.S. Pat. No. 1,563,889, issued Dec. 1, 1925, the tool disclosed in U.S. Pat. No. 1,851,497, issued Mar. 29, 1932, the painter's masking shield of U.S. Pat. No. 2,290,472, issued July 21, 1942, the shield for wall moldings of U.S. Pat. No. 2,332,579, issued Oct. 26, 1943, the guard for use in painting and cleaning operations of U.S. Pat. No. 2,517,220, issued Aug. 1, 1950, the wall protector of U.S. Pat. No. 2,538,743, issued Jan. 23, 1951, the surface masking shield of U.S. Pat. No. 2,672,122, issued Mar. 16, 1954, the spray shield of U.S. Pat. No. 2,842,093, issued July 8, 1958, the painting mask of U.S. Pat. No. 2,959,152, issued Nov. 8, 1960, the painters' door shield of U.S. Pat. No. 3,029,782, issued Apr. 17, 1962, the work attached paint shield of U.S. Pat. No. 3,380,435, issued Apr. 30, 1968, the baseboard protecting shield of U.S. Pat. No. 3,422,798, issued Jan. 21, 1969, the interior decorators' aid disclosed in British Patent Specification No. 1 400 406, published July 16, 1975, the paint shielding apparatus of U.S. Pat. No. 4,085,703, issued Apr. 25, 1978, the coating technique and apparatus of U.S. Pat. 3,415,675, issued Dec. 10, 1968, and the door casing hardware paint shield disclosed in U.S. Pat. No. No. 4,195,590, issued Apr. 1, 1980. For completeness' sake, reference may also be had to the picture frames of U.S. Pat. No. 3,237,332, issued Mar. 1, 1966, and U.S. Pat. No. 4,023,293, issued May 17, 1977, which would, however, not be practically usable as paint shields and which are not being proposed for this purpose.
Despite this seeming wealth of proposals, there persisted a heretofore unsatisfied need for practical and highly efficient spray shields of the type disclosed hereinafter, and for practical and highly efficient painting methods employing same.
In this respect, one may, for instance, consider the traditional and persistently followed approach to the painting of doors.
According to one prevailing approach, the installation of door knobs and cover plates is deferred until after the door has been painted. In practice, this introduces time delays and inefficiencies, particularly in large construction projects where the installation of the door and its final outfitting have to be conducted at different intervals.
Another prevailing approach to the painting of doors employs adhesive masking tape, which has to be carefully applied to and around the door knob and cover plate to shield the same when paint is being applied to the surface of the door. A particularly frequent application of this method concerns the repainting of previously painted doors in homes and in various private and public buildings.
In practice, the masking tape method is awkward, time consuming and requires considerable labor. Also, the adhesive of the masking tape tends to leave a residue on the masked surfaces, and the tape cannot always in practice be applied with the precision required for a satisfactory job.
For these and similar reasons, many painters try to do the job without any masking at all, thereby almost invariably leaving unsightly paint dabs on the door knob.
What has so far been said with respect to door knobs and cover plates applies also to painting around other raised objects or closed geometrical shapes or surfaces. Yet, despite their inherent and practical drawbacks, the prior art has not been able to relegate the mentioned approaches to obsolescence and to provide truly efficient and practical and widely acceptable substitutes.
The inherent inefficiencies and other drawbacks of existing shielding technology under consideration stands in sharp contrast to the increasing efficiency of spray and other painting methods. In practice, such improvements are to a considerable extent nullified by inefficient shielding and masking techniques.
With the advent of spray guns, particularly of the airless type, which emit paint at high velocity and narrow angles, the use of hand-held shields has become particularly attractive. However, that approach exposes the painter to real danger when relatively small objects or surfaces are to be shielded, since the impact of highvelocity paint jets on a painter's skin can cause serious injuries including the loss of fingers and entire limbs.
In retrospect, it may appear curious that cups and similar vessels which have been around for a long time apparently have not been creatively applied to the paint shield field, despite the above mentioned pressing needs. However, a review of proposals in that field shows a persistent lack of an acceptable solution.
In this respect, U.S. Pat. No. 2,925,064, issued Feb. 16, 1960, discloses a door knob paint shield composed of two half shells. U.S. Pat. No. 3,722,470, issued Mar. 27, 1973, discloses a paint shield composed of two sheets secured to one another so that they can be bowed outwardly from each other. Swiss Pat. No. 563 251, issued May 15, 1975, discloses a door knob paint shield having a can attached to a handle, and points out that the diameter of door knob escutcheons to be shielded is somewhat smaller than the inside diameter of the can or hollow cylinder.
Accordingly, the paint shield according to that Swiss Pat. No. 563 251 is not self-supporting on the docr knob. Rather, that paint shield can only be used for painting with a brush by hand, since it would have been too dangerous to use that paint shield for a high pressure spray paint operation, given the fact that such paint shield, as disclosed in the cited Swiss patent, has to be held over the door knob with one hand. As has become known in recent years, serious injuries with loss of fingers or limbs can occur if a hand is hit by high-pressure paint.
In particular, the paint shield disclosed in the Swiss Pat. No. 563 251 has to be held at its handle with one hand, while a paint brush is conducted around part of that paint shield with the other hand. During such painting operation, the hands have to be changed, since it is not possible or practical to guide the paint brush with one hand entirely around the hand and arm with which the paint shield has to be held at its handle according to the cited Swiss patent.
In practice, this need to change hands somewhat broadens the unpainted halo inevitably resulting from the use of that paint shield.
The paint shield according to the above mentioned U.S. Pat. No. 3,722,470 similarly leaves unpainted corners at the door knob cover plate, since it is practically impossible to stretch that cornered oval paint shield into a strictly cylindrical configuration. Rather, that paint shield comes open at the seams when such complete stretching against its initial configuration is attempted.
Use of the paint shield according to the above mentioned U.S. Pat. No. 2,925,064 also leaves unpainted portions about the cover plate of the door knob, since spraying paint is able to reach the cover plate through the lateral longitudinal cracks shown in that patent between the half shields.
U.S. Pat. No. 2,358,151, issued Sept. 12, 1944, discloses a mask for shielding a shaft or similar raised object. However, that approach inevitably leaves a wide unpainted circular portion at any otherwise painted surface around the shaft.
Paint shields which work with suction cups, as those disclosed in U.S. Pat. No. 3,335,703, issued Aug. 15, 1967, and British Patent Specification No. 18,938, A.D. 1914, as well as those operating with internal adjustment mechanisms, as disclosed in U.S. Pat. No. 4,196,692, issued Apr. 8, 1980, are similarly impractical for present purposes.
The same may be said of a variety of drinking cups, including the collapsible cups of U.S. Pat. Nos. 21,955, issued Nov. 2, 1858, and 61,084, issued Jan. 8, 1867, and 2,880,902, issued Apr. 7, 1959, the tumbler of U.S. Design Pat. Des. No. 221,135, issued July 13, 1971, the cup of U.S. Design Pat. Des. No. 223,704, issued May 30, 1972 and the cup of U.S. Pat. No. 4,168,676, issued Sept. 25, 1979, all disclosing a frustoconical configuration up to the top opening and a rolled or rounded circular brim about such top opening.
In practice, a frustoconical configuration would work against a retention of such cup on any raised door knob or similar object, and the rolled or rounded circular brim would also promote the occurrence of unpainted rings on the surface adjacent to a shielded door knob or similar raised object. While it cannot be clearly told from U.S. Design Pat. Des. No. 213,546, issued Mar. 18, 1969, what its author had in mind at the opening of its disclosed plastic drinking cup, there is nothing in his disclosure to suggest a deviation from conventional structure.
U.S. Design Pat. Des. No. 193,586, issued Sept. 11, 1962, discloses for its container for dairy products a circumferential rim which juts out radially around the region of the container cup opening. In practice, such a jutting rim portion would be even more detrimental than the rolled or rounded lips of the paint shield of the above mentioned Swiss Pat. No. 563 251 and of the drinking cup references. In particular, such a jutting portion would obstruct the paint brush or spray paint against reaching the entire surface to be painted, such as, the surface of the door immediately adjoining the shielded door knob cover plate or similar raised object.